Prior to the present invention, one-way restrictors for use in controlling the flow of pressurized fluids have been known and used. For example, a one-way restrictor of this type is known from the catalog Control Technology, Reg. 10, Page 1 and Page 2 of the WABCO Westinghouse Company, issued in Dec. 1975, under the description "Europe-One-Way-Restrictor".
The particular one-way restrictor taught in this reference includes an annular sealing element. Such annular sealing element is secured to a sleeve-shaped support member disposed within a housing member. A circumferential sealing lip forming a portion of the annular sealing element rests in a position such that it provides a seal against the surface of the wall of a bore formed in the housing of the one-way restrictor. Such circumferential sealing lip works in conjunction with this wall surface to form a check valve. The check valve can be brought into the open position by a pressure medium. The annular sealing element is located in the fluid pressure flow passage formed in this one-way restrictor by the outer surface of the sleeve-shaped support member and the surface of the inside wall of such housing bore. The fluid pressure flow passage is formed in the shape of an annular clearance. Such fluid pressure flow passage connects a pressure-medium inlet chamber with a pressure-medium outlet chamber. The inlet chamber is equipped for connection to a source of pressure medium and such outlet chamber is equipped for connection with a consumer of such pressure medium. In addition, in this prior art one-way restrictor, the inlet chamber and the outlet chamber are interconnected by way of an internal bore formed in the sleeve-shaped support member.
This one-way restrictor has a control member that is capable of rotating about its longitudinal axis positioned within the valve box. This control member includes a portion which extends into the internal bore of such sleeve-shaped member. The portion of such control member extending into such internal bore of the sleeve-shaped support member is essentially conically shaped. The conical-shaped portion of such control member in conjunction with the surface of the inside wall of the sleeve-shaped support member, which is disposed opposite the shell surface of such conical-shaped portion, thus define a second annular clearance. By way of this second annular clearance, the pressure-medium outlet chamber remains constantly connected for fluid communication with the pressure-medium inlet chamber. A guide member for such control member is disposed in such valve box. The control member, on its side which faces away from the conical-shaped portion, is provided with a threaded portion. This threaded portion of the control member threadedly engages a counterthreaded portion formed in such guide member.
The opening cross-section of the one-way restrictor is formed by the conical-shaped portion of the control member and the inside wall of the sleeve-shaped support member. Such opening cross-section can be changed by simply rotating the control member about its longitudinal axis. Due to the threaded engagement between the threaded portion of the control member and the threaded portion of the guide member such rotation of the control member will cause it to move in the direction of its longitudinal axis.
As can be seen from the above description of this prior art one-way restrictor, it is comprised of a rather large number of component parts which require a considerable amount of assembly effort. In addition, as is well known, the greater number of component parts increases the chances of something failing which will require repair or replacement.